The present invention relates to catheters, and more particularly to fixated catheters suitable for chronic sampling and delivery of fluids.
Catheters can be used to access specific portions of animal (including human) bodies to sample and deliver fluids. Although some applications need only short-term catheterization, many applications--for example, sampling or delivering fluids during experiments, tests, or therapies--require long-term or "chronic" placement of the catheter within a body. As is recognized by those of skill in the art, the migration of a catheter can ruin chronic experiments or therapies. For example, the study of biological activities or properties of new pharmaceuticals in experimental models often requires chronic sampling of the central nervous system fluid. To collect scientifically valid samples during this type of research, the catheter used to sample the fluids must not migrate or change position so that samples are withdrawn from the same point within the body.
Previous attempts to minimize migration of an indwelling catheter include attaching the catheter with screws and wire to bone. However, this attachment method can cause the catheter to wear out about the fixation point during body movements. Further, this method requires a painful, invasive procedure: the dissection of muscle to expose the bone for catheter attachment.
Other attachment methods, such as fixing the catheter in the subcutaneous tissue with discs and purse string sutures, either permit an undesirable amount of movement of the catheter or only maintain the catheter in place for short periods.
A variety of catheter and other medical devices have been designed for short-term and long-term insertion in a body. For example, U.S. Pat. No. 5,454,795 to Samson entitled "Kink-Free Spiral-Wound Catheter" issued Oct. 3, 1995 discloses a catheter for introduction to the vascular system in angioplasty procedures. A polymeric tube is spirally wound with "ribbons" to control the stiffness of the catheter. However, Samson discloses a catheter that slides smoothly through the vascular system rather than fixate in tissue for chronic use.
U.S. Pat. No. 3,399,668 to Lundgren entitled "Disposable Cholangiography Catheter" issued Sep. 3, 1968 discloses a disposable cholangiographic catheter for use in open abdominal surgery. The catheter has an exterior surface friction portion that cooperates with a tying element to prevent movement of the catheter in the bile duct. The friction portion can include ridges and depressions, a roughened abraded area, an adhesive layer on which fine grains of sand are permanently affixed, a tacky adhesive layer, or an adhesive that dries with a fine granular surface. However, to prevent catheter movement, the Lundgren catheter requires a tying element surrounding the cystic duct in which the catheter is inserted. This catheterization system thus necessitates an invasive and awkward surgical procedure for installation.
U.S. Pat. No. 4,955,859 to Zilber entitled "High-Friction Prosthetic Stent" issued Sep. 11, 1990 discloses a urethral stent for the non-surgical management of bladder outlet obstruction caused by an enlarged prostate. The stent includes either a textured fabric outer layer bonded to the tubular body of the stent or a silicon rubber outer jacket with a roughened outer surface. However, Zilber is directed to managing bladder obstructions, and thus fails to provide a fixating system for chronic access to deliver and sample fluids.
U.S. Pat. No. 4,266,999 to Baier entitled "Catheter For Long-Term Emplacement" issued May 12, 1981 discloses a catheter having a roughened exterior surface suitable for tissue ingrowth to provide adhesion between the skin and the roughened surface. However, the Baier catheter system fails to provide means of preventing migration of the catheter prior to tissue ingrowth.
U.S. Pat. No. 3,638,649 to Ersek entitled "Implantable Prosthetic Pass-Through Device" issued Feb. 1, 1972 discloses a catheter that allows skin tissue to form a permanent seal by using a tube having a roughened portion comprising "a myriad of hairy projections." Again, Ersek fails to provide a means of preventing migration of the device prior to tissue ingrowth.